The present invention relates to lamps for providing warning and/or status indications and particularly to lamps which provide such warnings and status illuminations in terms of the color or sequence of colors which the lamp is caused to radiate. The radiation from the lamp is omnidirectional so as to provide an omnidirectional beacon.
The lamp provides illumination, which can be in a multiplicity of colors, omnidirectionally, without the need of optical elements such as reflectors to direct the illumination in an omnidirectional pattern. The lamp provided by the invention may be implemented by a circuit board which extends along an axis about which illumination radiates omnidirectionally. The board has arrays of sources on opposite side surfaces thereof; preferably in lines of sources which parallel the axis. When multicolor illumination is desired, the sources in each line may radiate a different color. The board may be an upstanding printed circuit board mounted on another board which carries current to the sources in the array. The boards provide a subassembly which may mounted in the base of the lamp and covered by a transparent cover which may have striations so as to provide a Fresnel type lens. The base may be mounted on a panel so that the axis extends generally perpendicular to the panel. The sources are preferably LEDs which are mounted on the opposite side surfaces of the upstanding boards. These LEDs are preferably of the type which emit light in a relatively wide angle generally cone shaped radiation pattern which incudes an angle of about 120xc2x0, thereby avoiding blind spots in the omnidirectional radiation from the lamp.
LED lamps have been proposed wherein the LEDs are in a panel. Special reflectors are utilized to project illumination in a generally perpendicular direction away from the panel. See U.S. Pat. No. 5,765,940, issued Jun. 16, 1998; U.S. Pat. No. 5,184,114, issued Feb. 2, 1993; U.S. Pat. No. 5,436,534, Jul. 25, 1995; U.S. Pat. No. 5,594,433, Jan. 4, 1997; and U.S. Pat. No. 4,271,408, Jun. 2, 1991. Where omnidirectional radiation is desired, radial or circular arrays of LED sources have been proposed. In order to provide omnidirectional radiation from the sources emanating via the sides of the lamp, optics such as reflectors have been used to turn and distribute the illumination from the sources. See U.S. Pat. No. 5,224,773 issued Jul. 16, 1993, and Vukosic U.S. Pat. No. 5,929,788, issued Jul. 27, 1999, as well as the patents cited therein.
Accordingly, it is a principal feature of the invention to provide an improved lamp capable of providing omnidirectional illumination from an array of light sources carried on a printed circuit board, and particularly on opposite side surfaces of the board.
It is a further feature of the present invention to provide a lamp which emits light in a plurality of colors omnidirectionally, 360xc2x0 about an axis and can provide such colors selectively and in selected sequences.
It is still another feature of the invention to provide an improved multicolor omnidirectional warning or status indicator lamp which does not require optics for projecting and directing illumination from an array of lamps mounted in generally coplanar relationship on a board, thereby enabling to be implementations at lower cost than lamps having similar capabilities, which have heretofore been available.
Briefly described, a lamp in accordance with the invention, which provides illumination omnidirectionally 360xc2x0 about an axis, has a first board disposed perpendicular to the axis and a second board mounted on the first board and disposed along the axis. The second board has opposite sides. Light source elements, preferably LEDs are mounted in arrays on both of the sides of the second board. A transparent cover is disposed around the second board in assembled relationship with the boards, as by being connected to a base in which a subassembly of the first and second boards are disposed, with the second board upstanding from the base. Lamps in the arrays may be of different color along different lines in the arrays. These lines are preferably parallel to the axis and distributed over a substantial portion of the surfaces of the boards so that the illumination is in a wide angle beacon 360xc2x0 about the axis.